Bearing unit with improved inner race

ABSTRACT

A bearing assembly especially adapted for use as a trolley wheel for overhead conveyors. The assembly includes a multipart inner race in which one annular part, preferably machined from steel, bears the major loading on the assembly and the other annular part, preferably formed from sheet metal, bears only minor loading. The major load bearing inner race part extends on either side of the root diameter of the inner raceway and allows a full complement of balls to be inserted in place between the inner and outer raceways without heating and expansion, or contraction, or any other treatment of the inner or outer race parts. The minor load bearing inner race part is preferably clamped to the major load bearing part and provides a contoured extension of the major load bearing raceway for guidance and ball retention purposes. Preferably, the outer race outer circumference is curved to accommodate a sloped support track in overhead conveyors such that the loading force is directed through the balls to the major load bearing inner race part.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of application Ser. No. 06/124,556, filed Feb.25, 1980, now U.S. Pat. No. 4,323,288.

BACKGROUND OF THE INVENTION

This invention relates to improved bearing assemblies, and moreparticularly, to an improved bearing unit especially useful as a trolleywheel for overhead conveyors and an improved inner race structure forthat bearing unit.

In general, two types of ball bearing assemblies are available, namely,full-ball complement and retainer-type structures. Retainer-typeassemblies typically include an outer race, a single piece inner race, alesser number of balls between the two races than in a full-ballcomplement assembly, and a retainer or cage at least partially enclosingthe balls but not engaging either race for retaining the balls in theassembly. Retainer-type assemblies are generally used to handle lighterloads but are capable of attaining higher speeds principally due to thelesser number of balls and the resulting lower friction produced in theassembly due to the elimination of ball-to-ball contact.

In full-ball complement bearing assemblies, a series of balls is fittedbetween a multipart inner or outer race, or a single piece inner orouter race including a filling slot, and a single piece opposing race toenable insertion of the balls into the assembly.

One type of full-ball complement bearing assembly includes a two partinner race having two, symmetrical, machined, annular inner race partsincluding a curved raceway. The inner race dividing line is directlyunder or in line with the ball centers. The two parts are held togetherby a flanged hub or sleeve which is passed through both parts, expandedor riveted over at the end opposite the flanged portion. In this formeach of the inner race parts essentially bears an equal load.

Another full-ball complement bearing unit is shown in French Pat. No.502,354 and includes a two part inner race assembly where both partsappear to be fully machined and one includes a wider portion of the balltrack than the other. In this unit the outer race must be heated andexpanded to allow insertion of the ball members between the races.

Other types of multipart inner race bearing assemblies have a single,machined, annular inner ring and a flat washer or flat snap ringsubstituted for a missing raceway shoulder to retain the balls in theunit after assembly. This type assembly suffers from several drawbacksincluding excessive end play or axial runout which causes the bearingassembly to skew or improperly track, excessive wear on the balls due toa gap in and a lack of contour of the support surface for the balls andball engagement with the sharp corner of the snap ring or washer incertain circumstances, and excessive stress on the balls because of theinclusion of a cylindrical or "flat" raceway portion in the raceway areawhich provides principal load support which is not contoured to theshape of the ball.

In order to avoid the above-noted additional processing steps forexpanding the races to allow assembly, as well as the above functionalproblems, it has previously been necessary to utilize an inner raceassembly having two machined inner race parts which provide a wideopening for ball insertion, neither of which parts provides the majorityof the support and ball retention functions. Of course, such assembliesare significantly more expensive to manufacture than the presentinvention. The present invention is designed as a less expensive,full-ball complement trolley wheel or bearing assembly which can beassembled in its ambient state, is competitive from a price standpointwith retainer type wheels, and which, even in the partially machinedpreferred embodiment, includes the performance characteristics of moreexpensive, fully machined, full-ball complement wheels.

SUMMARY OF THE INVENTION

Accordingly, the present invention is a bearing assembly especiallyuseful as a trolley wheel is overhead conveyors including a multipartinner race which enables use of a full complement of balls and providesthe load bearing capabilities of currently known full-ball complementbearing assemblies. In addition, the assembly provides other functionaladvantages while requiring significantly less manufacturing time,processing and expense, thus making the wheel competitive from a pricestandpoint with retainer-type bearings and wheels.

Essentially, the invention uses a two-part inner race in which one innerrace part, preferably machined from steel, bears a major portion of theloading on the wheel. The one inner race part has a central aperturetherethrough, a raceway shoulder on one side of a radial plane extendingthrough the centers of the ball members supported between the inner andouter race parts and the minimum or root diameter of the inner race, anda curved raceway portion extending from the shoulder to at least theminimum or root diameter at the radial plane. The first inner race partalso includes an extension beyond the radial plane on the other sidethereof.

In one form of the invention, the extension of the first inner race partis a second shoulder on the other side of the radial plane, the secondshoulder having a diameter less than that of the shoulder on the oneside of the radial plane but greater than the minimum or root inner racediameter. The second shoulder allows a full complement of ball membersto be inserted between that major load bearing inner race part and asingle piece outer race without expansion, contraction or other specialassembly procedures on the races or balls. That second shoulder alsoprovides some resistance to the removal of the balls after insertion.

In a second alternative form of the invention, the first inner race partextension includes an annular, cylindrical surface extendingperpendicular to the radial plane and having a diameter equivalent tothe inner raceway minimum diameter. Assembly of the second form of thefirst inner race part with ball members and the single piece outer racepart is also enabled without any special processing, expansion orcontraction of these parts because the cylindrical, annular surface isthe same size as the minimum or root diameter of the inner racewaythereby allowing such insertion.

With either form of the first inner race part, a second inner race part,preferably stamped from sheet metal, is engaged by the first part on theother side of the radial plane on which the extension extends and has acurved shoulder forming another curved portion of the inner racewaywhich extends beyond the extension of the first inner race part on thatother side of the radial plane to guide and retain the ball members inthe inner and outer raceways. The second inner race part bears only aminor portion of the loading on the wheel or bearing unit while servingas a guide and retainer for a full complement of ball members duringoperation. The combined parts provide a contoured raceway resulting inminimal ball stress, low wear, and minimum end play or axial runout.

In other aspects, the major and minor raceway portions each have aradius of curvature slightly larger than that of the ball to provideoptimum ball contact with the raceways preventing high ball stress. Thefirst support is annular and is preferably machined from steel or othermetal. The second support is also annular and is preferably stamped fromsteel or other metal, fitted to the machined part, and clamped theretoby expanding a bendable flange into a recess on the first machined part.In the preferred embodiments, the outer circumference of the outer raceincludes a curvature which, in cooperation with a sloped support trackon which the assembly is designed to operate as a trolley wheel in anoverhead conveyor, and the camber angle at which the wheel is supportedon an overhead conveyor trolley bracket, causes any load imposed on theassembly to pass through the outer race, as close as possible to thecenter of lowermost ball and through the machined or major load bearinginner race part. This prevents undue force on the minor load bearing,stamped, inner race part.

The present invention is competitive with previously less expensive,retainer-type and other bearing and trolley wheel assemblies which donot include multipart inner race structures. The invention providesexcellent load bearing capabilities, minimal ball stress, high wearresistance, minimal end play or axial runout, and proper tracking withlittle skew of the assembly or wheel on its track because of the closelyfitted raceway contour and minimum end play. The invention is easy toassemble in its ambient condition without heating and expansion,contraction or special assembly processing of any of the inner and outerrace parts or ball members because of the provision of either the lowshoulder or the annular, cylindrical surface on the major load bearinginner race part followed by engagement and clamping of the stamped partto the machined part. Overall, the expense of the improved inner race ofthe present invention is greatly reduced from other full-ball complementtrolleys or bearing assemblies because of the lesser manufacturingrequirements and ease of assembly.

These and other objects, advantages, purposes and features of theinvention will become more apparent from a study of the followingdescription taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional elevation of the bearing assembly or trolley wheelof the present invention supported on an I-beam-type, overhead conveyortrack and mounted on a conventional trolley bracket;

FIG. 2 is a side view of the bearing assembly or trolley wheel shown inFIG. 1 but without the support track or trolley bracket or the seal andshield structure on the outer side;

FIG. 3 is a fragmentary, sectional, enlarged, elevation of the bearingassembly or trolley wheel of FIGS. 1 and 2;

FIG. 4 is an exploded, perspective view of the inner race parts of FIG.3;

FIG. 5 is a fragmentary, sectional, enlarged elevation of a modifiedform of the bearing assembly or trolley wheel of FIGS. 1-4;

FIG. 6 is a fragmentary, sectional elevation of another modified form ofthe bearing assembly or trolley wheel of the present invention;

FIG. 7 is a side elevation of the bearing assembly or trolley wheel ofFIG. 6 without the support track or trolley bracket shown in FIG. 6;

FIG. 8 is a fragmentary, sectional elevation of a fourth form of thebearing assembly or trolley wheel of the present invention; and

FIG. 9 is a side elevation of the trolley wheel of FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings in greater detail, FIGS. 1-3 illustrate afirst form of the bearing assembly or trolley wheel unit 10 of thepresent invention. Wheel or bearing 10 includes an outer race 12, aplurality or full complement of balls 30, an inner race assembly 35, asealing assembly 70 on one side, and a welch plug or full seal 90 on theopposite side. As is best seen in FIG. 1, the bearing or wheel assembly10 is designed for attachment to the nose or extending flange 13 at thehead of a trolley bracket 11 which also includes an intermediatesuspended portion 15 and an overhead conveyor chain engaging portion(not shown). When secured on nose or flange 13 of bracket 11, the wheelis designed to be supported on the sloped lower flange 21 of an I-beamoverhead conveyor track 19 as shown in FIG. 1. In the preferredembodiment of the invention, the slope of the flange 21, the camberangle at which the wheel or bearing assembly 10 is supported on trolleybracket 11, as well as the contour of the outer circumference of outerrace 12 are taken into account to determine the line of force loadingexerted on the wheel or bearing assembly during operation. As will beapparent from FIG. 1, an identical wheel and trolley bracket assembly isdesigned for support on the opposite, lower track flange 21a such thatthe chain engaging portions of two brackets (not shown) abut togetherand are received within the center link of an overhead conveyor chain inthe conventionally known manner.

As seen in FIGS. 2 and 3, outer race 12 is annular and includes oppositeside surfaces or faces 14, 16, side 14 being of a larger diameter thanside 16. An arcuate or curved outer circumferential surface 18 slopesbetween the larger diameter 14 and the smaller diameter 16 as shown inFIG. 3. Face or side surface 14 also includes smaller diameter, axialrecesses 20, 22 which extend in a stepped fashion toward a centralopening or aperture 26 extending through the outer race. Similarly, inface 16, a smaller diameter recess 24 with a radially inwardly bevelededge has been provided. Recesses 20, 22 and 24 receive portions of thesealing assembly 70 and welch plug 90, respectively, as will bedescribed hereinafter. A curved outer raceway 28 is also provided in thecentral aperture 26 at a position intermediate axial recesses 22, 24.Raceway 28 includes a radius of curvature slightly larger than thedesired ball size to reduce friction while minimizing stress on theballs and also to provide sufficient and adequate support therefor.

The essence of the present invention lies in the inner race assembly 35,best seen in FIGS. 1, 3 and 4. Inner race assembly 35 includes twoparts, namely, an annular principal inner raceway part or support 36,preferably machined from metal such as steel and case hardened to reducewear, and an annular secondary inner race part 50 preferably stampedfrom sheet metal such as steel and also case hardened and/or coined onits raceway portion to reduce wear. Primary inner race part 36 includesradially extending side faces 37, 38, side face 37 having a largerdiameter than face 38. A larger diameter shoulder 39 extends axiallyinwardly from face 37 and defines one side of a curved or arcuateraceway 40 extending from shoulder 39 through the minimum or rootdiameter 41 of raceway 40 to a second, or low shoulder 42 on theopposite side of the radial plane including the centers of balls 30 androot diameter 41. Raceway 40 has a radius of curvature slightly largerthan the radius of curvature of balls 30 such that optimum ball contactwith minimum stress buildup is provided. Low shoulder 42 has a diameterwhich is larger than the root or minimum diameter 41 of raceway 40 by adimension within the range of approximately 2% to 4% of the balldiameter. Thus, in the preferred embodiment of a four-inch trolley wheelassembly, including a full complement of balls of 1/2-inch diameter, lowshoulder 42 extends above or beyond the minimum or root diameter 41 bythe dimension within the range of approximately 0.010 to 0.020 inches.Further, in the preferred embodiment, wherein 1/2-inch diameter ballsare used, the dimension A (FIG. 3) which is the distance side surface orface 38 of primary inner race member 36 extends beyond the radial planeincluding the centers of balls 30 and the minimum root diameter 41, isequal to 0.084 inches or 16.8% of the ball diameter. Preferably,dimension A is held to a range of approximately 15% to 17% of the balldiameter.

Primary inner race member or support 36 also includes a central aperture44 extending therethrough in which is formed an annular recess 45 havinga radially inwardly sloped, annular surface 46 extending outwardly tothe side surface or face 38 as shown in FIG. 3. Sloped surface 46 hasits minimum diameter immediately adjacent side surface 38 and is adaptedto receive a bent or expanded flange from the secondary inner race part50 as will be explained hereinafter.

Secondary inner race part 50 includes a radially extending intermediateportion 52, an annular, inwardly extending flange 54, and a curved,outwardly angled extending shoulder 56 best seen in FIG. 3. The insidesurface of intermediate portion 52 abuts and engages the radiallyextending side surface or face 38 of primary inner race member 36 and,in the preferred embodiment, is held in that position by the bending orexpansion of flange 54 into and against the sloped surface 46 in recess45. When bent, the smallest diameter of flange 54 defines an apertureextending centrally through the secondary inner race part 50, whichdiameter is no smaller than the diameter of central aperture 44 inprimary inner race part 36. Shoulder 56 curves outwardly and away fromprimary inner race part 36 to define a secondary raceway portion 60which also has the same radius of curvature as raceway portion 40 whichis slightly larger than that of the balls 30. Raceway 60 is aligned withraceway portion 40, although not continuous therewith, to provideguidance for the balls as they roll in the primary raceway 40 and, withlow shoulder 42, also serves to retain the balls in the primary raceway40. However, shoulder 56 and raceway 60 are not designed to bear a majorpart of the loading on the assembly. The major loading is borne byprimary inner race part 36 and raceway 40. Hence, manufacture ofsecondary inner race part 50 from sheet metal is fully sufficient andstrong enough for operation of the assembly 10 which can provide loadbearing capabilities fully consistent with conventionally knownfull-ball complement trolley wheel or bearing assemblies having innerrace structures of a fully machined or different design.

FIG. 5 shows a modified form 10' of the bearing assembly or trolleywheel of FIGS. 1-4 wherein like numerals illustrate like parts to FIGS.1-4. The primary difference between embodiments 10 and 10' is theinclusion of a cylindrical, annular extension 42' on inner race member36' on the side of the radial plane on which the second or minor innerrace part 50 extends. Thus, embodiment 10' includes shoulder 39 and acurved, contoured raceway 40' having a curvature slightly larger thanthat of the ball members 30. Raceway portion 40' extends from shoulder39 to the minimum or root diameter 41 at the radial plane. Beyond theradial plane, cylindrical surface 42' extends laterally to side surfaceor face 38' of the primary inner race member 36'. The diameter of thecylindrical extension surface 42' is that of the minimum or rootdiameter of the inner raceway. In this form, the secondary inner racepart 50 is the same as that in embodiment 10 and engages extending sidesurface or face 38' and extends radially and axially outwardly ofcylindrical surface 42' in a curved fashion with curved surface 60 toform an extension of the curved, contoured raceway 40' in the samefashion as in embodiment 10. The dimension A' (FIG. 5) is preferablyheld within the same range 15% to 17% of the ball diameter as inembodiment 10.

Embodiment 10' provides the advantage of even easier insertion of ballmembers 30 between inner race part 36' and outer race part 12 becausethere is no low shoulder over which the ball members are inserted. Thecosts for embodiment 10' are reduced as compared to bearing 10 becauseit is easier to manufacture and assemble. As in embodiment 10, thesloped or contoured outer race circumference 18 in combination with thesloped track 21 causes the major load on the bearing assembly to beborne by inner race part 36', and more specifically, the contoured,curved race portion 40' of that inner race part. Secondary inner racepart 50 provides only a minor low bearing support and principallyprovides guidance and retention for the ball members 30. The annular,cylindrical surface 42' is not engaged by the ball members during theirmovement because of the retention and guidance of the secondary innerrace part 50. Hence, stress buildup is also prevented in embodiment 10'because the cylindrical portion does not bear any significant loadingand because ball members 30 are engaged by a curved, contoured racewayincluding portions 40' and 60.

As will be understood from FIGS. 1, 3 and 5, assembly of either bearingor trolley wheel units 10 or 10' is as follows. Primary inner race part36 or 36' is centered within outer race 12 in a suitable support and afull complement of balls 30 are inserted into position between outerraceway 28 and primary raceway 40 or 40' over the low shoulder 42 orcylindrical surface 42'. In the preferred embodiment of a 4-inch trolleywheel, 131/2-inch diameter balls are so located. The dimension of lowshoulder 42 described above is sufficient to assist in retaining theballs in place during assembly and to help do so during operation but issmall enough to allow the above insertion to occur. No size modificationof the outer race, inner race parts 36, 36' or 50, or ball members 30 isnecessary to allow such assembly. Assembly occurs at ambient, roomtemperature conditions with no heating or other expansion processes, orcontraction or any other special assembly processing being necessary.During operation, low shoulder 42 helps retain the balls in the primaryraceway 40 with the help of shoulder 56 and raceway extension 60 onsecondary inner race part 50 as described above.

After the assembly of the balls between the inner and outer raceways,secondary inner race part 50 is positioned within recess 45 of primaryinner race part 36 or 36' and flange 54 is expanded or bent with anappropriate tool into that recess and against the sloped surface 46 toretain the primary and secondary inner race parts together as describedabove. Thereafter, the nose or extending flange 13 of a trolley bracket11 may be inserted through central apertures 44 and 58 of the inner raceparts and bent or expanded outwardly as shown in FIG. 3. Such expansionor clamping positively retains inner race parts 50 and 36 or 36'together.

If desired, sealing members forming the sealing assembly 70 may betelescoped over the extending flange or nose 13 of bracket 11 andagainst abutting shoulder 11a prior to insertion of that nose or flangeto the inner race members described above. When flange 13 is bent orcrimped against inner race assembly 50, the sealing members will beclamped against the outer side surface 37 of primary inner race part 36and retained in sealing position as shown in FIGS. 3 and 5. The sealingassembly 70 is of the type described and claimed in U.S. Pat. No.3,537,725, assigned to the same assignee as is the present invention,the disclosure of which is hereby incorporated by reference. Assembly ofwheel or bearing units 10 or 10' to the trolley bracket 11 is completedby insertion of welch plug or full seal 90 in recess 24 as shown inFIGS. 1, 3 and 5.

Referring now to FIGS. 6 and 7, a second embodiment 100 of the bearingunit or trolley wheel assembly of the present invention is illustratedwherein like numbers indicate like parts to those in embodiment 10.Embodiment 100 differs principally from embodiment 10 by the inclusionof slightly modified primary and secondary inner race parts 110 and 120.Primary inner race part 110 is the same as part 36 except that recess112 for receiving the flange 122 of inner race part 120 is not slopedand extends parallel to the axis of the wheel assembly. Secondary innerrace part 120, which is otherwise exactly the same as inner race part50, includes flange 122 which also extends parallel to the axis and iseither slip-fitted or press-fitted into recess 112. Part 120 is retainedin engagement with primary inner race part 110 by means fo a flangedcentral hub 130 having a threaded central bore receiving a fasteningbolt or stud 132 through the apertured head of a trolley bracket 134 asshown in FIG. 6.

For shipment and operation purposes, the outermost seal 118 in thesealing assembly included in embodiment 100 includes an inwardlyextending flange 116 designed to be received in and bent intocooperating recesses 114 radially opposed with one another on the outercircumference of hub 130 and the inside diameter of primary inner racepart 110. Flange 116 therefore retains the hub 130 within the inner raceparts 110, 120 as is described and claimed in copending U.S. patentapplication Ser. No. 57,588, filed July 16, 1979, and assigned to thesame assignee as the present invention, the disclosure of which ishereby incorporated by reference. As is explained in application Ser.No. 57,588, the head of trolley bracket 134 includes an eccentricallylocated projection 136 which is cylindrical but offset from the axis ofbolt 132 and hub 130 for receipt in the correspondingly offset circularrecess 138 in the outer end of hub 130 thereby preventing rotationbetween hub 130 and bracket 134. In turn, flange 116 prevents rotationbetween inner race parts 110 and 120 with respect to hub 130 and bracket134 in the manner described in application Ser. No. 57,588. Operationand load bearing capabilities of embodiment 100 are equivalent to thoseof embodiment 10.

Referring now to FIGS. 8 and 9, a third embodiment 150 of the bearingassembly or trolley wheel unit is shown wherein like numbers illustratelike parts to those included in embodiment 10. The essential differencebetween embodiment 150 and embodiment 10 is the inclusion of a differenttype of fastening stud received through the central apertures 44, 58 ofprimary and secondary inner race parts 36 and 50'. Stud 152 alsoincludes a head or flange 154 having an interior bevel or chamferreceived against a correspondingly beveled exterior of secondary innerrace part 50' to hold that part against the primary inner race part.Other than such bevel, part 50' is the same as part 50. Stud 152 alsoincludes an intermediate diameter portion 156 engaging the centralapertures 44, 58 and a reduced diameter fastening portion 158 designedto be received through the head of a trolley bracket such as that at 134in FIG. 6. A retaining collar 160, having a cylindrical protrusion 162of the same diameter as intermediate shaft or stud portion 156, istelescoped over fastening stud portion 158 against the intermediatediameter portion. Collar 160 is designed to abut against the outersurface of a trolley bracket head and to secure the sealing members ofsealing assembly 70 against the exterior side 37 of primary inner racepart 36 as shown in FIG. 8. Accordingly, head 154 on stud 152 and collar160 serves to positively retain primary and secondary inner race parts36, 50' together and sealing members of assembly 70 thereagainst whenthe stud and wheel assembly is secured to the head of a trolley bracket.

As will now be understood, any of the embodiments 10, 10', 100 or 150 isuniquely designed to assure that the loading on the bearing assembly ortrolley wheel passes through and is primarily borne by the primary innerrace part 36, 36' or 110 such that the secondary inner race parts 50,50' or 120 provide only a guidance and retention function and bear onlya minor portion of the loading on the assembly. In this connection, theline of force shown in FIG. 1 which represents the direction of theloading in the preferred embodiment, begins at an annular line aroundthe outer race outer circumference on the inner side of the radial planethrough the ball centers and inner raceway root diameter, at which thatcircumference engages the sloped support track surface, through or asclose as possible to the center of the lowermost ball 30 on the lowerside of the wheel, and through the primary inner race parts 36, 36' or110. As such, the principal load on the wheel assembly is borne by thepart 36, 36' or 110. The line of force extends at angle Beta as shown inFIG. 1. Such loading creates a minimal force moment on the bearing suchthat the upper balls, located approximately 180° from the loaded ballzone, ride against the secondary inner race part 50 with very littleforce.

In the preferred embodiments, this line of force directed through theprimary inner race parts 36, 36', or 110 is determined by severalfactors including the draft angle of surfaces 21 or 21a on I-beam 19which, in the preferred embodiment, for a 4-inch I-beam, ASTM-A36, isslightly less than 91/2°. The line of force loading also depends on thecurvature of the outer circumference of outer race 12 which in thepreferred embodiment, has a radius of curvature of 3 inches for a 4-inchtrolley wheel. Finally, the line of force direction also depends on theangle of camber at which the trolley wheel is supported on the trolleybracket, i.e., in the preferred embodiment 11/2° from the horizontal asshown in FIG. 1. With the above dimensions, the preferred embodiment ofa 4-inch trolley wheel in accordance with the present invention has beenfound to have the line of force pass 0.007 inches from the center of thelower ball and to its right as shown in FIG. 1. Optimally, this line offorce would pass through the center of the ball but dimensionaltolerances in manufacturing may cause the line of force to be slightlyoff center. The line of force has been found to be acceptable if it iswithin a range of plus or minus 0.020 inches from the center of thelower ball, i.e., plus or minus 4% of the ball diameter which is1/2-inch in the preferred 4-inch trolley embodiment.

Accordingly, the present invention provides the ability for ease ofassembly of a full complement of ball bearings between the inner andouter races over the low shoulder 42 followed by secure attachment ofthe guide and retainer secondary inner race part to the primary innerrace part. The two inner race parts provide a closely controlled, curvedinner raceway which keeps axial runout or end play to a minimum allowingthe wheel to track properly with little skew on the support track. Inaddition, expense in manufacture is greatly reduced because thesecondary inner race part can be stamped and mass produced and machiningis only required for one of the inner race parts. That machined innerrace part bears the primary load in the assembly providing long life.Even greater life and less wear are expected when one or both inner raceparts are case hardened and/or coined. The inner race parts inaccordance with the invention are also susceptible of being fastened tosupporting brackets or trolley brackets in various ways as shown aboveand can accept and include various sealing structures as described.

While several forms of the invention have been shown and described,other forms will now be apparent to those skilled in the art. Therefore,it will be understood that the embodiments shown in the drawings anddescribed above are merely for illustrative purposes, and are notintended to limit the scope of the invention which is defined by theclaims which follow.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. In a bearing assemblyhaving inner and outer race means for supporting a plurality ofanti-friction ball members therebetween, and a plurality of such ballspositioned between inner and outer raceways on said race means, theimprovement comprising:said inner race means having first support meansincluding a major portion of said inner raceway for supporting theprimary portion of any load on said assembly and second support meansengaged with said first support means and including a minor portion ofsaid inner raceway for retaining and guiding said ball members andsupporting a minor portion of any load on said assembly; said majorraceway portion on said first support means extending on both sides of aradial plane of said assembly which passes through the center line ofsaid ball members and the root diameter of said inner raceway; saidfirst support means including a first shoulder having a diameterslightly larger than said root diameter of said inner raceway to allowinsertion of said ball members between said inner and outer racewaysprior to assembly of said second support means without heating orotherwise resizing or modifying any part of said inner or outer racemeans or ball members during assembly, said first shoulder alsoproviding resistance to removal of said ball members after insertion;said first support means also having a generally radially extendingsurface adjacent said first shoulder and a recess; said second supportmeans including a portion engaging said generally radially extendingsurface of said first support means and a flange bent into and engagingsaid recess to retain said inner race members in engagement.
 2. Thebearing assembly of claim 1 wherein said major and minor racewayportions on said first and second support means each have a radius ofcurvature slightly larger than that of said ball members.
 3. The bearingassembly of claim 2 wherein the radius of curvature for each of saidmajor and minor raceway portions is equivalent.
 4. The bearing assemblyof claim 1 wherein said ball members each have an equivalent diameter;said first shoulder diameter being larger than said root diameter ofsaid inner raceway by a distance within the range of approximately 2% to4% of said diameter of said ball members.
 5. The bearing assembly ofclaim 1 wherein said first support means is a first, annular, inner racepart also including a second shoulder with a diameter larger than saidfirst shoulder, said second shoulder defining the opposite end of saidmajor raceway portion, and a pair of spaced, radially extending, sidesurfaces; said second support means being a second annular, inner racepart and including a radially extending portion abutting one sidesurface of said first inner race part and an extending shoulder largerthan said first shoulder on said first inner race part, said extendingshoulder including said minor raceway portion.
 6. In a bearing assemblyof the type having a plurality of anti-friction balls; outer race meanshaving an outer raceway for supporting said plurality of balls; andinner race means spaced radially inwardly of said outer race means andhaving an inner raceway in opposition to said outer raceway forsupporting said plurality of balls, the improvement comprising:saidinner race means having a minimum or root diameter; said bearingassembly including a radial plane passing through said outer race means,the centers of said balls, and said root diameter of said inner racemeans; said inner race means including a first annular inner race memberhaving a first raceway extending from a first shoulder having a firstdiameter on one side of said radial plane to a second shoulder on theopposite side of said radial plane, said second shoulder having a seconddiameter less than said first diameter and slightly larger than saidroot diameter, a generally radially extending surface adjacent saidsecond shoulder, and a recess, and a second annular inner race memberhaving a portion engaging said generally radially extending surface ofsaid first inner race member and having a second raceway forming anextension of said first raceway and extending to a third shoulder of adiameter larger than said second diameter; said second shoulder having adiameter sufficient to allow said plurality of balls to be inserted intoposition intermediate said inner and outer raceways without heating orotherwise resizing or modifying of any part of said inner or outer racemeans or anti-friction balls during assembly, and to resist removal ofsaid balls once in position whereby said first inner race part providesprincipal load bearing support for said outer race means and balls whilesaid second inner race part provides ball retention and guidance andlesser load bearing support than said first inner race part; said secondinner race part also having a flange bent into and engaging said recessto retain said inner race members in engagement.
 7. The bearing assemblyof claim 6 wherein said balls each have an equivalent predetermineddiameter; said second diameter being larger than said root diameter by adistance within the range of approximately 2% to 4% of saidpredetermined ball diameter.
 8. The bearing assembly of claim 6 whereinsaid first inner race part is machined from metal; said second innerrace part being stamped from sheet metal.
 9. The bearing assembly ofclaim 8 wherein at least one of said first and second inner race partsis hardened.
 10. The bearing assembly of claim 6 wherein said innerraceway formed by said first and second inner race members has a radiusof curvature slightly larger than that of said balls.